Size effect on IMC growth in micro-scale Sn-3.0Ag-0.5Cu-0.1TiO2 solder joints in reflow process

The influence of joint size on the interfacial reaction in Sn-3.0Ag-0.5Cu-0.1TiO(2) solder joints was investigated in this study. The thickness and grain size of the intermetallic layer were characterized by scanning electron microscope (SEM). Results show that both the thickness and grain size of the intermetallic compound (IMC) increases with the increase in joint size. The growth exponents for both IMC layers and grains are determined by curve-fitting to study the growth kinetics of IMC in wetting reaction. Results reveal that the growth exponents for IMC layer and grains increase with increase in joint size. The size effect might be due to the difference of Cu concentration distribution near the IMC interface in the molten solder. A two dimensional finite element method was adopted to investigate the kinetics of the Cu diffusion behavior in solder joint during the reflow process. Results reveal that the diffusion of Cu atoms might be influenced by the coarsening of the scallop like grains. (C) 2016 Elsevier B.V. All rights reserved.